Well Mainer, my opinion would be a bolt action 30-06. Why? It's the only rifle I really ever messed with. I currently use a Remington 710 30-06. I've used other 06 models in the past and was satisfied with all. However I have heard a few people raving up the Thompson Center Encore models accuracy and such. I think that's the kind that breaks open to load/unload. But when you say fast and flat, lightweight and smaller size a 270 comes to mind. GOOD LUCK TO YOU.